DNA and RNA Bases. In DNA, there are four different bases: adenine (A) and guanine (G) are the larger purines. Cytosine (C) and thymine (T) are the smaller pyrimidines.
Gretna is the second-largest city and parish seat of Jefferson Parish, Louisiana, United States. Gretna is on the west bank of the Mississippi River, just east and across the river from uptown New Orleans. It is part of the New Orleans â Metairie â Kenner Metropolitan Statistical Area. The population was 17,736 at the 2010 census.
Gretna-area historical tornado activity is slightly below Louisiana state average. It is 20% greater than the overall U.S. average. On 12/6/1983, a category F4 (max. wind speeds 207-260 mph) tornado 24.7 miles away from the Gretna city center injured 25 people and caused between $5,000,000 and $50,000,000 in damages.